Disclosed herein are blends of polyphenylene ether sulfone and silicone polyester carbonate, methods for making the blends, and articles derived from such blends. The blends have a particularly advantageous combination of properties.
There has long been interest in developing thermoplastic resins that can resist burning. A specific area of concern is in developing plastics for transportation applications, such as rail cars and airplanes. Various evaluation techniques have been developed to test the effectiveness of such materials, for instance Federal Aviation Regulation (FAR) 25.853. In this test, sometimes referred to as the Ohio State University (OSU) rating, the time for a sample to reach peak heat release, the amount of energy released after 2 minutes and the peak heat release energy are measured. Lower peak heat release values and longer time to reach peak heat release are desirable.
Polyphenylene ether sulfones (PPSU) are well known engineering thermoplastics made by condensation polymerization. PPSU resins have good flame resistance, but in terms of the very demanding requirements for large fire resistance, such as in aircraft and rail interiors (for example FAR 25.853 (d)) they do not meet the combined requirements of a 2 minute heat release below 55 kilowatt minutes per square meter (KW-min/m2) and peak heat release below 55 kilowatts per square meter (KW/m2). In other instances a longer time to reach peak heat release (for example greater than 120 seconds) is desired.
The PPSU polymers also have an exceptionally high impact strength without rubber modification, however in many applications such as transportation and electronic applications, their high melt viscosity makes them difficult to mold into large thin walled parts.
For the foregoing reasons, there exists an unmet need for compositions comprising PPSU that have the aforementioned 2 minute heat release, peak heat release properties as well as having sufficiently low melt viscosity to allow molding of large thin walled parts.